Testing Brake Fluid for Water Saturation: Old, New, Stored, and Used!

I test some Motul RBF600 in various states of age and use to try and see at what point hydrophilic/hydroscopic brake fluid is saturated. I test old fluid left exposed to the air, old fluid stored in as sealed a manner as I could, new fluid, and fluid just after being bled out of my NSX. Again, I'm not currently sponsored by anyone up to and including Motul.
Motul:
www.motul.com/
The FIRM:
gorally.com/
Brake Fluid Tester like mine:
www.amazon.com/Tester-Indicat...
Lap of the World
______________________________________________
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Website: www.lapoftheworld.com
Track Feature Videos from my Lap of the World:
• Track Features
NSX-Specific Videos:
• NSX Specific
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• Gallardo Specific
Just the Laps (minimal-no "presenting"):
• Just the Laps
0:00 Intro (that didn't age well)
1:09 New Tool!
1:44 Brake Fluid 101 and why testing is important
5:22 How the tester works
6:22 The test samples / conditions
10:00 Testing the fluid
13:02 Asking more questions from the results
14:15 How long does it take exposed brake fluid to spoil?
15:10 What does this mean for tech inspections using these fluid testers?
16:28 Closing thoughts

[@LapoftheWorld]

Video now chaptered! "Heard" on the rambling in some of these now-old videos so making a quality-of-life pass for those finding the channel this way! Thanks for watching.

[@bigbadassballer71]

"Looks like 2020 is gonna be a pretty good year"

[@LapoftheWorld]

Yup, totally jinxed it, lol.

[@leftmorningstar6954]

@@LapoftheWorld yes lol

[@bigbadassballer71]

@Yirlani very cool

[@ArjjunSingh]

Thanks! I needed to see this!

[@margaritoponcetorres1482]

So helpful, thanks a lot for the video!

[@Jiggysaw]

Great video!!! I have recently purchased a 2017 RX350, not sure if the previous owner has flushed brake fluid but the master cylinder looks clean clean clean. I will go ahead and get a tester to make sure the moisture level isn't excessive. This will help guide my vehicle service decisions. Thank you for posting, this is very good content!

[@LapoftheWorld]

Thanks for stopping by, I'm glad you found the video useful! This type of thing definitely applies to ALL vehicles, not just track-used cars.

[@onefastboi14]

Very good video! I'd be curious as to how long it'd take milage wise for the fluid to go from dry to wet. I do a fair bit of driving, normally 20-40k miles a year and use Motul RBF 600 brake fluid as my primary fluid in my car as the other fluids I have used didn't seem to last as well or hold up to spirited driving. Will have to give the brake fluid tester pen a try and check to see how my fluid looks as I have some fluid stored in similar fashion to your older bottle of motul rbf 600.

[@chrisgoes9610]

Useful thanks for sharing. I would be curious for a test with how fluid stored in its container, seal broken, cap on. I had a container circa 2 years old, looks spent.

[@lobbyrobby]

Well I just as well sub cuz this is like the 5th video of yours I've watched. Good stuff. Do you have a video on brake pads? I'd like to find a good daily pad that would get me through a couple track days per year.

[@LapoftheWorld]

I've been using Hawk HP+ for years now. At least for my ~2900lb ~290hp car at my skill level I haven't manage to exceed their capability on the track, and they still have decent bite even dead-cold. The down-side is they dust a LOT. For a heavier / higher HP car, you may want to go a step more aggressive, but I think for any kind of 'real' track use I'm not sure I'd go any less aggressive unless your car is really light/low power (i.e. NA/NB Miata range). In the Hawk range, the step up would be a DTC-30. The step down would be the HPS. I'm not sponsored, for the record, it's just what I'm familiar with. There are equivalent ranges of Carbotech pads, and maybe a few others depending on your car (e.g. Pagid, Endless, Stoptech, Brembo).

[@lobbyrobby]

@Lap of the World I have a 2020 mustang gt pp1. 6 piston Brembo on the front. From what I'm learning the factory pads might be ok for a couple track days. Especially for me as I'm a newbie.

[@LapoftheWorld]

​@@lobbyrobby Yeah, for the first few events it would be unusual to kill even normal-ish pads. I'd say if you were going to do anything it would be to make sure your brake fluid is the good stuff. Boiling fluid is far and away the most common brake failure at the track, especially before you train good braking habits that help mitigate heat. I'm not sure what the factory fill is on those, but I'd look into some Motul RBF 600, ATE Type 200, or if you want "the best" (as of right now) Castrol SRF.

[@lobbyrobby]

@Lap of the World 👍

[@Doglifepro]

I've always been curious. I imagine the region you live in or general humidity level would make a difference too. I need one of those testers!

[@LapoftheWorld]

We definitely get the ambient humidity here. You'd definitely want to take steps to store somewhere without big temp swings that coupe lead to condensation in an opened/resealed container.

[@AstroCreepSpeedShack]

Interestingly enough, 9 out of the 10 bottles of MOTUL RBF660 I've opened in the last 2-3 years have been the much darker amber/maple syrup color like your "bad" sample on the right. Every other brake fluid I've used in the past has been the much lighter amber color like your "good" samples. I always believed there was a fairly obvious color coralation with saturated/bad fluid, but since I've never actually tested the RBF660, I've really got no idea. Anybody used RBF660 and had it be dark when new, freshly opened?

[@LapoftheWorld]

Interesting observation. My tests with '600 at least would lead me to believe there might not be total cause/effect relationship between color and saturation. I know some locals I think who use 660 though so maybe I'll see if I can sneak by next time they're going to crack open a bottle.

[@BigBear--]

Motul lists the color of the RBF660 as Amber. Which is supposed to be darker than what they list for RBF600 and DOT 5.1.

[@anidiotinaracingcar4874]

I can't believe how quickly is absorbed 4% water!

[@odortiz]

I have heard of race teams “cooking” their new brake fulid in a sauce pan, to make sure it’s really dry fluid. Care to try that? Keep in mind, brake fluid is flammable, so i would guess cooking it at about 200 degrees and seeing if your unused fluid that spoiled in 2 days, can be dried. And perhaps a test where you have a graduated cylinder with dry fluid, and add .3% water and see where it lights up on the tester.

[@LapoftheWorld]

I'll do some research there. Are you saying they were basically "reducing" their brake fluid to use by cooking out the water, or just testing samples to validate BP? I do know there are more advanced meters that can measure the current boiling point of fluid non-destructively vs. just registering a saturation %. That would be the next step in my opinion to validating manufacturer claims and seeing if new fluid met the claims.

[@odortiz]

Lap of the World i don’t think they were reducing it. I think they were making sure it was completely dry. It was years ago i saw it and have never seen it again. I’m just curious if you can lower the water percentage by getting it to evaporate like you would in engine oil.

[@steved0x]

When are you coming down to The FIRM, I'm only an hour away and haven't been there in a while so it might be time :) Maybe I will see you there!

[@LapoftheWorld]

This coming weekend 2/22-2/23 with Just Track It. Feel free to say "hi". I'm there both days, though will probably head out a little before quitting time Sunday.

[@steved0x]

@@LapoftheWorld I am in Sebring that (well I guess at this point it is "this") weekend. Dang it, well see you next time!

[@LapoftheWorld]

@@steved0x Definitely keep an eye out as I have several more tracks to go in Florida. Sebring is one I have done and is always a ton of fun.

[@ross4681]

Interesting. Dug deep and found a bottle of Caltex Dot 4. It had been opened and just a little used for a moped 8 to 10 years ago. The cap had been put back on the bottle and placed on a shelf in the garage. I tested it and it reads less than 1% water.

[@LapoftheWorld]

Interesting. Apparently the shelf life can be long if stored correctly.

[@LionhartM]

I got a tester today and was disappointed to find out that the brand new brake fluid I just bought from O'Reilly's tested at 3% :/. That's exactly the same as my old fluid

[@LapoftheWorld]

Weird. Makes you wonder if the container was somehow compromised, considering it seems to keep when stored appropriately.

[@fabianbotea8469]

You have to just tip the electrodes in the liquid...not dive completely. It more accurate reading in this way.

[@derek8766]

Brake fluid is hygroscopic it will absorb moisture. Only Dot 3, 4 and 5.1 is hydrophilic but DOT 5 is not because it can not dissolve in water. Good demonstration video though.

[@LapoftheWorld]

Thanks! Hydroscopic is probably the best technical term and one I included in the video description but for whatever reason 'philic was in my head when I got to talking. You're correct about the silicone-based DOT 5 not having that same issue, BUT it's so narrow in it's usages with respect to modern cars I didn't feel the need to go out on that limb in this video😁.

[@334trax2]

@@LapoftheWorld ignorant question coming, Is DOT 5 better than fluid in video? Can I use it in my 2019 VW GTI? I will be on track too. Thanks

[@LapoftheWorld]

@@334trax2 Not so much ignorant. DOT 5 really is not that common. DOT 5 fluid has a different base stock (silicone) than DOT 3, DOT4, and DOT 5.1. As a result it's not compatible with those other fluids. It may also be incompatible with modern anti-lock braking systems. So most likely, no, you shouldn't try DOT 5 in your GTI. Any of the high-end DOT 4 "racing" brake fluids should do well though, ATE Type 200, Motul RBF 6___, Castrol SRF, and others.

[@odortiz]

334 TRAX an interesting thing about silicone fluid, is since it doesn’t absorb water, condensation could eventually form water droplets and settle in the low parts of the system, and stay there corroding ferrous metals. It‘s probably unlikely to ever happen, but if water ever made it in, it might never get out, unlike with the regular fluids. It’s probably only suitable for never-driven museum pieces.

[@334trax2]

@@odortiz maybe so 👍

[@334trax2]

New subscriber I heard of you from a JUST TRACK IT member saw you coming back from the FIRM. I just started track events so I'm always wanting to earn more. I'll be at Roebling March 28th and 29th with JUST TRACK IT.

[@LapoftheWorld]

JTI were awesome hosts and they seem to have a very good instructor corps judging by those I spoke with at the FIRM. I haven't been to Roebling yet, but have heard it's fun. I'm not sure if I'll make that JTI event in late March or not, but it's at least in pencil on my calendar at this point.

[@334trax2]

@@LapoftheWorld come on out. FYI I really like the NSX

[@CptSlow89]

So if its closed its fine. Nice.

[@LapoftheWorld]

Just to be clear, the lid was on *and* it was in a plastic zip bag. In that situation though, it does seem to have at least a few months' shelf life after the seal is broken.

[@htx713cc8]

those type of cheap testers are so inaccurate they are truly completely useless in almost all cases. try adding water and see how off they are. I like the idea of testing this and would love to know as well but this test is not accurate enough to tell us anything. For regular everyday cars just use good fluid its already got twice the wet boiling point and is so far above what your brakes will ever get to unless you did manage to reach boiling point on the street in which case your in prison or dead so it doesn't matter to you and if your like me my car has been flushed once in 20 years the race bike never had more than 6 months lol.

[@LapoftheWorld]

I did actually run a test with new fluid that I added some water to just to see if it did change as advertised (it did). While not super accurate, these testers are good for an all/nothing scenario. In other words, it's saturated or not. If it shows yellow/red then you're probably due a flush before track duty. Obviously There's some margin if you're running something like SRF with a super high wet BP, but as dumb as they are a tester like this might save a novice a headache or expensive lesson. For better or worse they're also the kind of tester I've seen used in tech inspections.

[@jcaleca60]

Good video just the audio is too low

[@LapoftheWorld]

Thanks for watching and I appreciate the feedback, always trying to improve!

[@wilderaruquipa7350]

Español pues...

[@syllinx1]

Porn for gearheads. Just had my brake fluid flushed after 37000 miles on a 2013 crv.

[@Roy-xu2nb]

Thanks for the video, but c'mon, you made a 17 mins video what could've been a 4 mins video

[@henrycruz45cal]

For a buck more you could get a pen that shows a digital reading

[@rondhole]

Brake fluid degrade not only by water contamination but from heat also. When it gets dark, it means it has been exposed to heat more. In hybrid cars, the brake fluid is always looks new and the water contaminant is always less than 1% even after 5 years 50k miles

[@LapoftheWorld]

As a data point here, Porsche still calls for 20k miles or 2 years for a brake flush on a Taycan. The hydraulic brakes even on EVs use effectively the same tech that dates back to the 90s, just with bigger hardware and more sophisticated ABS, so water absorption is still the primary means of degradation. As such, I'd still flush any car, hybrid, EV, or ICE at least annually if I'm taking it to a track. I get saving some money here and there, but when, "F-around and find out" ends up with my car in the wall because I didn't want to spend $60 and 2 hrs...🤷‍♂

[@rondhole]

@@LapoftheWorld everyone call 2y interval for making money in dealership